All this talk of PreRunners, Let's put together the Ultimate (Budget) Desert MJ

I love my MJ, but it's built for rocks. If I found another one for cheap, I would definitely want to turn it into a pre-runner, but on a serious budget (ie, no air bumps, no 9100s, no coilovers, etc)


So, my thinking:

Drivetrain:
-Stock 4.0 with normal intake/exhaust mods
-AW4 auto, or AX15 manual? is stick or auto better for desert use
-np231 (or D300, which would be easy since no front D-shaft) I figure leave the t-case so you can use low if you want it for a trail.
-Toy 8" or Ford 9" rear, trussed, geared, spooled (detroit?)
-Front beam (2wd), 3" .25 wall tube with D44 knuckles/steering/brakes

Suspension:
-Regular coils front, lifted about 4-5 inches
-4 link plus panhard (trackbar), run the uppers just up/inside the frame-rails, run the lowers a few inches below the frame rails, each arm 30" or more (since clearance isn't as critical as rockcrawling)
-poly bushings for all link ends?
-Rear keep it spring under, but lifted about 4 inches, lot's of thin leafs and longer shackle
-Bilstein 7100, non-resevoir shocks at all 4 corners (or 5150s?)
-Big Poly bumpstops all around

Body/Cage:
-Interior cage and a little tube for the back
-modify stock bed (keep just the sides?) to keep a kinda stock look
-cut the front fenders nice and high
-misc. reinforcements; steering box, motor mounts, etc
-gut the interior except the essentials


slap some 33s on aluminums on it and get jumpin!

what am I missing? any answers to the questions above? any things you would do different, while still keeping it on a tight budget?

I would think you could do all that for about $2000 over the cost of the initial purchase.

Let's do it! You thinking of something like a JeepSpeed version of an MJ?

The FIRST thing to get the gas ax would be the beam front axle. Swap in a junkyard TTB setup from an 80s/90s Ranger.

Ditch the T-case.

Automatic trans.

9" from a 70's Ford.

Sever chop job on the inside of the bed, leave only the bedsides.

Why are all your buildups "budget"? Budget + desert racing do not belong, nor are they usually found, in the same sentence.

It's like trying to find a "budget" girlfriend. You think you got a deal until you wake up the next morning.....

CRASH

okay, no t-case, makes sense, check

auto, that's what I've heard, check

9", great, they have tons of aftermarket, check

chop job, already planned, check

TTB... hmmm, I understand where you're coming from, but I'm not so sure I like it. Yes it would be better, but the difference in geometry and fabrication would be something completely different than what I'm familiar with... I'd have to look into it more before deciding, but a beam axle would just be SOO easy.

Budget? yeah... well... that's what you get when you're 19 (20 next week, woohoo). yeah, most desert racing trucks are about a half million bucks, so that's why I'm wondering if it would be reasonable to put something decent together for a few grand. Honestly, it won't happen in the next couple years unless I came across a nice MJ with good 4.0 for $100, and we all know how common those are

And about my girlfriend; she's definitely one of a kind, a hotty and low-maintenance

I love XJ and to a lesser degree MJs...BUT THEY ARE NOT PRERUNNER MATERIAL!!
Come on now people....can you all say thin unibody ..That is the long and short of it. They simply can not take the abuse....that is without forking out hugh amounts of money to make them last. Not to make them fast.
In the short run they have great power to wieght ratios...are light weight...and are abundant and cheap. But that is it.
Listen to the Jeepspeed guys.....don't take it out without breaking something, need 7100 series shocks....truss and support everything. Dollar to dollar a good Baja Bug will stomp a Jeep.
Now don't you all go red in the face on me and question my parentage.
I drool over any well built off-road machine..and a Jeepspeed XJ is a prime example of a toy taken to the nth degree. Love em. But if you want a practical desert toy to take at speed....try a buggy, don't thin out the supply of XJs just to bend it into a worthless pretzel...
Okay....I supose I should take my wippin' now from those who dissagree....
SHOOT! :twak:

I gotta agree with Jump This...to a point. If you are loking for a "budget" prerunner you better start with something a lot more stout, like a 2wd ranger ect. not an XJ. The XJ would take way too much moola to make a good prerunner.

Hehe would it even be possible to thin out the XJ supply?

You Guy's are being too harsh, a long bed MJ can make a good Pre-Runner (as good as anything with a similar wheelbase), all it takes is comparable $$$. You could start a pre-runner project with a buggy and be dollars ahead, but it's not "street legal" for fun on most BLM/USFS roads, and other truck based choices will run into the $$$$ as well (and TIB F150's and Rangers are like armpits, and weight a ton more than the MJ).

The MJ frame is not a real frame, it's a unit frame under the cab and real frame under the bed, so a cage to tie in the cab & front CA mounts to the spring hangers and upper shock mounts is needed (the F**d's need this as well).

Reinforce the arm and spring mounts, and revise/reinforce the shock and engine mounts. Build/buy stronger control arms. Reniforce the steering box and track bar mounts (again, the F**d's need this as well).

Remove all the extra weight (maybe everything but the A/C ).

All of the above work is time in the workshop (mostly labor) so the cost is not too great (the same can be said of a F**d project base).

2WD is a better lightweight base, and with an auto you do not need the low range t-case (t-case only with 4WD). If your stuck in 2WD, you are either going too slow or got caught behind someone who is too slow (back out and hit it faster for the go-around). 4WD is better for chase duty (cannot risk a stuck excuse when it's the racecar that needs the tug, a mile down the course) and 4WD is better for multi-purpose duty. If it's fast fun you want, 2WD and a locker will go 100% of the places the race courses will lead you, at the risk of getting stuck off the course. Chose what works best for your fun (2WD fast at the risk of getting stuck when playing wheeler, or 4WD not-as-fast and help the 2WD's who do get stuck).

Choose springs carefully. Up front the Currie progressive rate 250/300's, RE ZJ5.5's or Rancho's for the high rate (or go coilover if the budget is deep pocket). In the rear use the MJ pack in the stock spring-under configuration and/or run a 62" F150/Ranger main or pack with new mounts. Keep the rear rate fairly light compared to the front, and do not sweat the ground clearance (not like rockcrawling) as the ruts will not be too deep for 35's. The spring choices do not need to be expensive to go fast (not with an XJ/MJ's lightweight) as used Rancho springs can be found cheap for a start.

Long travel is great, but limited travel (even less than the 10/12" Jeepspeed rule range) will ride fairly nice with well positioned poly or rubber stops (air-bumps are nice, but not "budget"). Spending more initial time on making the stops work as progressive secondary springs, rather than exploiting the long travel focus we normally see in rockcrawling, will pay off in the fun and speed result.

Focus on the budget on good shocks (get quality rebuildable shocks if possible). Twenty years ago the Rancho 9000 were the best around, and for a twin/triple tube shock they are fine, but a quality monotube will better resist fade (even if the dampening is too light when they are cold). You can save the shocks for when the budget can afford the cost, but it will also make the most difference in the ride.

The rear axle can be a D44/9" swap, but the non-C-clip early D35 is servicable. Any axle needs a truss (as the speed does not shock load the axle shafts like rockcrawling, but the impacts will bend the tubes & housing). If the budget is a choice between a beefier axle or better shocks, milking the D35 with a truss and a drive tillitbreaks attitude is probably the better choice (spend the $$$ on shocks).

The Class 7S MJ's of the late 80's and early 90's did not have the quality springs or shocks, control arms, or bumpstop options available today and they were typically as fast as the 1/2-1600 buggies and even the Class 10 (1650cc unlimited suspension) buggys. The technology has helped these other classes go faster, and Jeepspeed has shown that the XJ/MJ can still post competitive times (sometimes the fastest lap times in MDR races).

The excess overflow racer technology available today can make a good budget pre-runner without the excessive cost of Jeepspeed (the need to live under the limited rules in competition for 500 miles adds detail costs that are not required of a pre-runner). A 30-35 MPH average speed over 50 miles (50-75 MPH in the rough wash/road course straights) is very fun, but stretching the endurance to 500 miles (within the rules) can be taxing and costly, an expense a pre-runner can avoid if the speed is only 10 MPH slower. This is the main difference between a racer and pre-runner: the cost of staying within the rules and the extended hammering of the chassis at max-speed. The constant speed for hours on end really beats the suspension, bushings, springs, and shocks, abuse that a pre-runner does not have to endure. The cost saved in not double reinforcing everything, to stay within the rules and last, can be saved or spent on better quality shocks and longer travel with bumpstops that work to save the balance of the chassis from abuse.

The ultimate pre-runner MJ would be much like starting with a Jeepspeed base (the big dollar detail costs) and ignoring the rules to achieve extremely long travel. The suspension would be a highly modified linkage with bypass shocks and coilover struts (well outside the Jeepspeed rules), essentially an unlimited tube buggy with an MJ cab and bed-skin and drivetrain. Most people will comment an Ultimate MJ pre-runner a waste of money (when a used fullsize long wheelbase truggy can be found cheaper), but they already say that about building XJ rockcrawlers (compared to used tube framed rockbuggys). It's all what you want, and unless you really are racing (where the rulebook limits the configuration as much as technology) any good looking ride can get you down the road with a good measure of fun.

:cheers:
Thank you Ed that was a great post. I say go for it I'm thinking of doing something very similar but withw 2.5 5 speed truck. I have to admit I never thought about useing some 44 ends on a leanth of .25 wal to make a better front beam set up, good idea. I had thought about using a 2wd WJ setup for the sweet brake setup. If i can just find a cool leagle place to go play at. but I planed on just re gearing and trusing a non c-clip 35 and beat the snot out of it till it breaks since the better axles I need for some 4x4 projects i'm working on.

Ed.....you have too much time on your hands......
Rick

That top MJ in the picture is Dan Fresh's. He cleans up in score racing and flys for having all the limits his class has. The top jeepspeeds are very limited compaired to the rangers and toyotas out there and normally posts higher average speeds than all but the class 7 unlimited trucks. My friend traded his modified ranger for a longbed comanche. It was easier to get travel out of the front end of the jeep, and the steering is so much better than the ranger. The other thing to remember is that unless you get a very new ford, you start with an engine that you really don't need to pour money into for more power. Anyways, I'd choose a comanche.